Characteristics and Habitat of the Eel: Complete Guide

The European eel: a fascinating snake-like fish

The eel, a fascinating snake-like fish, possesses unique characteristics and varied habitats that make it a remarkable species in our aquatic ecosystems. Belonging to the Anguillidae family, this glass eel in adulthood alternates between fresh and salt water throughout its extraordinary life cycle. Its elongated, cylindrical body gives the silver eel exceptional agility in the various environments it frequents.

In the aquatic food chain, the European eel occupies an important intermediate position, feeding on small invertebrates and fish while serving as prey for many predators. Moreover, this migratory fish plays a crucial ecological role in the ecosystems it traverses throughout its life.

Interesting facts about the eel:

• The eel can live up to 85 years in certain conditions
• It has the ability to breathe through its skin in addition to its gills
• This snake-like fish can move on land for short distances
• Its reproduction remains partially mysterious to scientists
• The European eel is classified as a critically endangered species

As a result of overfishing and habitat degradation, the silver eel (Anguilla anguilla) now appears on the IUCN Red List of Threatened Species, highlighting the importance of its protection.

Physical characteristics of the eel

Unique morphology of this snake-like fish

The eel presents unique physical characteristics that allow it to adapt to its particular lifestyle. Its elongated, cylindrical body, slightly compressed laterally, gives the glass eel turned adult an efficient sinuous swimming motion. Additionally, its slimy skin is covered with protective mucus that facilitates movement and protects against infections.

One of the most remarkable physical adaptations of the European eel is undoubtedly its ability to change coloration according to its environment and developmental stage. Thus, young eels (glass eels) are transparent, while adults generally present a dark back and lighter belly.

Furthermore, this snake-like fish has small scales deeply embedded in its skin, giving it a smooth feel to the touch. Its dorsal, caudal, and anal fins are fused, forming a single continuous fin that surrounds the back of its body, thus maximizing its propulsion in water.

Table of eel characteristics:

Habitat and distribution of the eel

The natural environment of the glass eel and adult eel

The eel’s habitat is remarkably varied thanks to its complex life cycle that crosses different ecosystems. However, adult eels are mainly found in freshwater rivers, lakes, ponds, and marshes where they can camouflage themselves in mud or among rocks.

The geographical distribution of this snake-like fish spans several continents. The European eel (Anguilla anguilla) is present throughout most of Europe, North Africa, and Western Asia. In contrast, the American eel (Anguilla rostrata) is mainly found along the eastern coast of North America.

Eels have remarkably adapted to their varied environments. Their muscular body allows them to swim against currents and even move outside water to circumvent obstacles. Nevertheless, they prefer muddy bottoms where they can bury themselves during the day, being primarily nocturnal.

Preferred zones of the silver eel

The eel is mainly found in slow-flowing water courses, marshy areas, and calm bodies of water with abundant vegetation. In addition, certain species like the European eel can also live in brackish water in estuaries and coastal lagoons.

The migration of the eel constitutes one of the most extraordinary phenomena in the animal world. Adult eels undertake a journey of several thousand kilometers from continental waters to the Sargasso Sea to reproduce, while young larvae make the reverse journey to colonize freshwater.

Reproduction and behavior of the eel

Social behavior of the snake-like fish

The social behavior of the eel is primarily solitary, although groupings may be observed during migrations. Eels are territorial and actively defend their living space against intruders.

Reproductive cycle of the European eel

The reproductive cycle of the eel remains one of the most mysterious in the animal kingdom. After spending between 5 and 20 years in freshwater, eels undergo a physiological metamorphosis called “silvering” that prepares them for reproductive migration. Consequently, they cease feeding, their eyes enlarge, and their coloration becomes silvery.

European and American eels then undertake an extraordinary journey to the Sargasso Sea, located in the Atlantic Ocean. It is there that reproduction takes place, although scientists have never directly observed it. After spawning, adults probably die of exhaustion.

Development of glass eels

Eel larvae, called leptocephali, are transparent and leaf-shaped. They drift with ocean currents for several months before reaching the coasts. At this point, they transform into glass eels (transparent young eels) that ascend waterways to begin their life in freshwater.

A particularly interesting behavior of the eel is its ability to adapt to different salinities, allowing it to move from freshwater to saltwater during its migrations. Thus, this remarkable physiological adaptability testifies to the unique evolution of this species.

FAQ on eels

How to recognize an eel?

The eel can be recognized by its elongated snake-like body, slimy skin, and its dorsal, caudal, and anal fins fused into a single continuous fin. The characteristics of the eel also include a pointed head with a slightly prominent lower jaw and small round eyes.

What does an eel eat in its natural habitat?

In its natural habitat, the eel is an opportunistic predator with a varied diet. It feeds primarily on small fish, worms, crustaceans, mollusks, and aquatic insects. The characteristics of the eel such as its night vision and developed sense of smell help it locate prey.

How to raise eels in captivity?

Raising eels in captivity requires a spacious tank with sandy or muddy bottom, well-oxygenated water, and hiding places. The ideal temperature is between 18°C and 24°C. The habitat of the eel in captivity must be secure because they can easily escape. The diet can include worms, small fish, and special pellets for carnivorous fish.

Why is the European eel an endangered species?

The European eel is threatened due to multiple factors: overfishing (especially of glass eels), habitat destruction, obstacles to migration (dams), water pollution, introduced parasites, and climate change. The characteristics of the eel and its habitat are severely affected by these pressures, resulting in a decline of more than 90% of its population since the 1970s.